Female checkerspots typically lay their eggs in clusters on a plant that serves as food for the larvae. Common food plants include plantain, beardtongue, Indian paintbrush, aster, rabbit brush, and other members of the figwort and sunflower families. The eggs hatch in a few weeks and the young caterpillars that emerge feed together in a cluster; some species make a retreat of silk webbing similar to that of tent caterpillars. Checkerspot caterpillars are usually black or dark brown, sometimes with stripes of orange or other colors, and have ornamented spines along their backs. The caterpillars feed and molt several times over a period of several weeks. They spend the winter, curled up in a leaf or other protected site. In spring, they form a pupa inside a protective capsule, or chrysalis, and begin to change into adult butterflies. The speckled, camouflaged chrysalis hangs from a leaf or branch. The complete adult butterfly emerges in early summer and begins a new cycle.
By studying checkerspots, scientists have learned a great deal about the ecology, evolution, and conservation of insects and other animals. Many of the plants eaten by checkerspot caterpillars contain toxic chemicals called iridoid glycosides. These chemicals deter most other insect plant feeders, but checkerspot butterflies are attracted to plants with iridoid glycosides, and the chemicals actually stimulate more rapid feeding by checkerspot caterpillars. Some species of checkerspot caterpillars retain these chemicals within their bodies, making themselves unappetizing to birds and other potential predators.
Detailed studies of checkerspot genetics and ecology have shown that different populations within a single species may vary in their wing pattern and in their relationship to their environment. For example, Chalcedon checkerspot butterflies from different populations prefer to lay their eggs and feed on distinctly different host plants. Such findings emphasize that scientists need to consider the ecological characteristics of populations within each species. This is an important concept in conserving species and is one reason why biologists have focused increasingly on protecting distinctly different populations or subspecies.
Scientists have also shown that some checkerspot populations live in isolated patches of habitat where food and nectar resources are located, with occasional movement of individuals between the patches. If the butterflies within a particular patch become extinct, the empty patch will be recolonized after a period of time by butterflies moving from nearby patches. Although not all patches of habitat are always occupied by the butterflies, the butterfly population in the region as a whole persists as a result of this pattern of extinction and recolonization of local patches. A regional population may decline if occasional movement between the patches is prevented by disturbances such as land development. A population may also be in jeopardy if patches of habitats in a region are destroyed, even if that species does not currently occupy some of the habitat patches. Loss of critical habitat patches is now threatening the existence of many butterfly populations, including some checkerspots.
Scientific classification: Checkerspots are included in the genera Euphedryas and Chlosyne in the butterfly family Nymphalidae. The Chalcedon checkerspot is Euphedryas chalcedona. Checkerspots are closely related to the crescent and patch butterflies.